JP6826717B2 - Modifier for Cellulose Ester Resin, Cellulose Ester Resin Composition and Optical Film - Google Patents

Description

The present invention relates to a modifier for a cellulose ester resin, a cellulose ester resin composition, and an optical film.

Conventionally, cellulose ester resin has been used as a photographic support because of its toughness and transparency. In recent years, cellulose ester resins have been used as optical materials for devices that handle polarized light, such as liquid crystal displays, because they are not only optically highly transparent but also optically isotropic. It is used as a support for a child protective film, an optical compensation film that improves the display when viewed from an oblique direction, and the like.

When a film made of the cellulose ester resin is used as a protective film for a polarizing element used for a polarizing plate which is a member for a liquid crystal display, the cellulose ester film can sufficiently prevent the infiltration of moisture such as moisture. Since this is not possible, there are problems such as deterioration of the polarizer and peeling between the polarizer and the protective film. Therefore, conventionally, a film obtained by adding a plasticizer such as triphenyl phosphate to a cellulose ester resin to impart moisture permeation resistance has been used as a polarizer protective film.

In recent years, there has been an increasing demand for thinner liquid crystal displays. As the liquid crystal display becomes thinner, the thinner protective film for the polarizer is being studied. When the film thickness of the polarizing element protective film containing the plasticizer and the cellulose ester resin is reduced to a required level, there is a problem that the moisture permeation resistance is remarkably lowered. It is conceivable to increase the amount of the plasticizer in order to obtain sufficient moisture permeation resistance, but in that case, problems such as bleeding out of the plasticizer and a decrease in the strength of the film itself may occur. It has also been proposed to improve the moisture permeation resistance of the film by adding a polymer (polyester or polyether ester) having a weight average molecular weight in a specific range to the cellulose ester resin (Patent Document 1), but a sufficient effect. Was not obtained.

Since then, various types of polyester compounds have been studied as modifiers for cellulose ester resins (for example, Patent Documents 2 to 6). Patent Document 2 describes a polyester in which the end is sealed with an aromatic monocarboxylic acid in a condensate of an aromatic dicarboxylic acid and a glycol having a low carbon number. Patent Document 3 describes a polyester in which the end is sealed with an aliphatic monoalcohol or an aliphatic monocarboxylic acid in a condensate of an aliphatic dicarboxylic acid and a glycol having a low carbon number. Patent Document 4 describes a polyester in which the end is sealed with ether alcohol in a condensate of a polybasic acid containing a specific amount of aromatic dicarboxylic acid and a polyhydric alcohol. Patent Document 5 describes polyester which is a condensate of aromatic dicarboxylic acid and glycol. Patent Document 6 describes a polyester in which the end is sealed with acetic acid or benzoic acid in a condensate of an aliphatic dicarboxylic acid, an aromatic dicarboxylic acid, and a glycol having a low carbon number. However, the moisture permeation resistance of the film formed by using the modifier and the cellulose ester resin described in Patent Documents 2 to 6 is not sufficient, and at a level requiring another additive (moisture proofing agent). there were. Therefore, there is a demand for a polyester-based modifier that can impart excellent moisture permeation resistance to a cellulose ester resin.

JP-A-2002-022956 Japanese Unexamined Patent Publication No. 2006-282987 Japanese Unexamined Patent Publication No. 2009-046531 JP-A-2009-173742 Japanese Unexamined Patent Publication No. 2010-138379 International Publication No. 10/08721

A main object of the present invention is to provide a modifier that imparts excellent moisture permeation resistance to a cellulose ester resin and does not impair the transparency originally possessed by the cellulose ester resin. Another object of the present invention is to provide a cellulose ester resin composition containing the modifier, and an optical cellulose ester resin film made from the resin composition and having excellent moisture permeability and transparency. ..

As a result of diligent studies by the present inventors, polyester containing an aromatic divalent alcohol residue and an aliphatic dihydric alcohol residue as divalent alcohol residues was used as a modifier for a cellulose ester resin. We have found that the above problems can be solved. The present invention has been completed based on such findings.

That is, the present invention relates to the modifier for cellulose ester resin, the cellulose ester resin composition, and the optical film shown in Items 1 to 9 below.
Item 1. The following formula (1) or (2):

[In formulas (1) and (2), A ¹ , A ² and A ³ represent the same or different aliphatic dicarboxylic acid residues. G ¹ , G ² and G ³ indicate the same or different divalent alcohol residues, and the divalent alcohol residues include aliphatic dihydric alcohol residues and aromatic dihydric alcohol residues. .. n is an integer of 1 or more. ]
A modifier for a cellulose ester resin containing an ester compound having a structure represented by.
Item 2. Item 2. The modifier for a cellulose ester resin according to Item 1, wherein the ester compound has a number average molecular weight of 500 to 2500.
Item 3. Item 3. The cellulose ester resin according to Item 1 or 2, wherein the molar ratio of the aliphatic dihydric alcohol residue to the aromatic dihydric alcohol residue in the ester compound is 95: 5 to 20:80. For modifiers.
Item 4. Item 3. The modifier for cellulose ester resin according to any one of Items 1 to 3, which has a structure represented by the formula (2) and has an alcoholic hydroxyl group without sealing both ends. ..
Item 5. Item 2. The modifier for cellulose ester resin according to any one of Items 1 to 3, which has a structure represented by the formula (1) and has both ends sealed with monoalcohol.
Item 6. Item 5. The modifier for cellulose ester resin according to Item 5, wherein the monoalcohol is an aromatic monoalcohol.
Item 7. Item 2. The modifier for a cellulose ester resin according to any one of Items 1 to 6, wherein the acid value of the ester compound is 3 mgKOH / g or less.
Item 8. Item 8. A cellulose ester resin composition containing the modifier for cellulose ester resin according to any one of Items 1 to 7 and a cellulose ester resin.
Item 9. An optical film containing the cellulose ester resin composition according to Item 8.

According to the present invention, it is possible to provide a modifier that imparts excellent moisture permeation resistance to a cellulose ester resin and does not impair the transparency originally possessed by the cellulose ester resin. By adding the modifier for cellulose ester resin of the present invention to the cellulose ester resin, the film made of the cellulose ester resin composition containing the modifier and the cellulose ester resin has excellent transparency and transparency resistance. Wetness can be imparted.

The modifier for cellulose ester resin, the cellulose ester resin composition, and the optical film of the present invention will be described.

1. 1. Modifier for Cellulose Ester Resin The modifier for cellulose ester resin of the present invention has the following formula (1) or (2):

[In formulas (1) and (2), A ¹ , A ² and A ³ represent the same or different aliphatic dicarboxylic acid residues. G ¹ , G ² and G ³ indicate the same or different divalent alcohol residues, and the divalent alcohol residues include aliphatic dihydric alcohol residues and aromatic dihydric alcohol residues. .. n is an integer of 1 or more. ]
Includes an ester compound having a structure represented by.

<Ester compound>
The ester compound is a reaction product of an aliphatic dicarboxylic acid and a dihydric alcohol (aliphatic dihydric alcohol and aromatic dihydric alcohol). That is, the ester compound is a polyester obtained by esterifying an aliphatic dicarboxylic acid and a dihydric alcohol, and is a polymer having a repeating unit based on the aliphatic dicarboxylic acid and the dihydric alcohol.

When the modifier for cellulose ester resin of the present invention contains the ester compound, the transparency and moisture permeability of the optical film obtained from the cellulose ester resin composition containing the modifier and the cellulose ester resin are remarkably improved. Can be improved.

Here, the aliphatic dicarboxylic acid residue refers to the remaining group obtained by removing the hydroxyl group from the two carboxyl groups of the aliphatic dicarboxylic acid. The divalent alcohol residue refers to the remaining group obtained by removing hydrogen from each of the two hydroxyl groups of the divalent alcohol.

The number of carbon atoms of the aliphatic dicarboxylic acid forming the aliphatic dicarboxylic acid residue represented by A ¹ , A ² and A ³ of the above formulas (1) and (2) by the reaction is preferably 2 to 15. It is more preferably 2 to 10, and particularly preferably 2 to 4.

Specific examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimellinic acid, suberic acid, 3-ethyl-3-methylglutaric acid, azelaic acid, heptane-4, 4-dicarboxylic acid, sebacic acid, undecandicarboxylic acid, dodecanedicarboxylic acid, 1,1-cyclopropanedicarboxylic acid, 1,1-cyclobutanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1 , 4-Cyclohexanedicarboxylic acid, 1,1-cyclopentanedioacetic acid, maleic acid, fumaric acid, acetylenedicarboxylic acid and the like.

Among these aliphatic dicarboxylic acids, preferably, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-Cyclohexanedicarboxylic acid, malonic acid, and fumaric acid, with particular preference being oxalic acid, malonic acid, and succinic acid.

The aliphatic dicarboxylic acid includes a carboxylic acid derivative such as an esterified product, an acid chloride product, or an acid anhydride. These can be used alone or in combination of two or more.

The divalent alcohol residues represented by G ¹ , G ² and G ³ in the above formulas (1) and (2) include both an aliphatic dihydric alcohol residue and an aromatic dihydric alcohol residue. Is done. By containing both an aliphatic dihydric alcohol residue and an aromatic dihydric alcohol residue in the modifier, it is possible to further improve the moisture permeation resistance while maintaining the transparency of the obtained film. it can. Aliphatic dihydric alcohols and aromatic dihydric alcohols are used as dihydric alcohols that form divalent alcohol residues represented by G ¹ , G ² and G ³ of the above formulas (1) and (2) by the reaction. Use in combination.

The aliphatic dihydric alcohol may be linear or branched chain, and may have an alicyclic structure. The number of carbon atoms in the aliphatic dihydric alcohol is preferably 2 to 15, more preferably 2 to 6, and particularly preferably 2 to 3.

Examples of the aliphatic dihydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, and 2,2-dimethyl. -1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1 , 5-Pentanediol, 1,5-hexanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl- 1,3-Pentanediol, 1,2-Cyclopentanediol, 1,3-Cyclopentanediol, 1,2-Cyclohexanediol, 1,4-Cyclohexanediol, 1,4-Cyclohexanedimethanol and 1,1-Cyclohexane Diethanol and the like can be mentioned.

Among these aliphatic dihydric alcohols, ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol and 1,4- Cyclohexanedimethanol, particularly preferably ethylene glycol and 1,2-propanediol.

These aliphatic dihydric alcohols may be used alone or in combination of two or more.

The aromatic dihydric alcohol refers to a compound having at least one aromatic ring structure in the molecule and having two hydroxyl groups. The hydroxyl group in the compound may be directly bonded to the aromatic ring, or may be bonded to another functional group such as an alkyl group bonded to the aromatic ring. The number of carbon atoms in the aromatic dihydric alcohol is preferably 6 to 25, more preferably 6 to 15, and particularly preferably 6 to 10.

Examples of the aromatic divalent alcohol include hydroquinone, resorcinol, 2,2'-biphenol, 4,4'-biphenol, 2,2-bis (4-hydroxyphenyl) propane, and 1,1-bis (4-). Hydroxyphenyl) -1-phenylethane, 2,2-bis (4-hydroxyphenyl) butane, bis (4-hydroxyphenyl) diphenylmethane, 2,2-bis (3-methyl-4-hydroxyphenyl) propane, 1, 1-bis (4-hydroxyphenyl) ethane, bis (4-hydroxyphenyl) methane, 2,2-bis (4-hydroxy-3-isopropylphenyl) propane, 1,3-bis (2- (4-hydroxyphenyl) ) -2-propyl) benzene, 1,4-bis (2- (4-hydroxyphenyl) -2-propyl) benzene, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,2-benzenedimethanol, Examples thereof include 1,4-benzenedimethanol, 1,2-benzenediethanol, 1,4-benzenediethanol and 2,2'-(1,3-phenylene) bis (2-propanol).

Among these aromatic divalent alcohols, preferably hydroquinone, resorcinol, 2,2'-biphenol, 4,4'-biphenol, bis (4-hydroxyphenyl) methane, 1,2-benzenedimethanol, 1 , 4-Benzene diethanol, 1,2-benzene diethanol and 1,4-benzene diethanol, particularly preferably hydroquinone, resorcinol, 1,2-benzene diethanol, 1,4-benzene diethanol, 1, 2 -Benzene diethanol and 1,4-benzenediethanol.

These aromatic dihydric alcohols may be used alone or in combination of two or more.

The molar ratio of the aliphatic dihydric alcohol residue to the aromatic dihydric alcohol residue in the ester compound is preferably 95: 5 to 20:80, preferably 90: 10 to 30:70. It is more preferable that there is, and it is particularly preferable that it is 80:20 to 40:60.

The ester compound may contain the structure of the above formula (1) or (2), and other structures are not particularly limited. Both ends of the ester compound may not be sealed with an end sealant or may be sealed. When the ester compound is not terminal-sealed, the terminal is preferably an alcoholic hydroxyl group. Examples of such an ester compound include those having a structure represented by the above formula (2) and having an alcoholic hydroxyl group without sealing both ends. When the ester compound is terminally sealed, it is preferably sealed with a monoalcohol. Examples of the monoalcohol include an aliphatic monoalcohol and an aromatic monoalcohol, and it is more preferable that the monoalcohol is sealed with the aromatic monoalcohol. Examples of such an ester compound include those having a structure represented by the above formula (1) and having both ends sealed with a monoalcohol such as an aromatic alcohol. As the ester compound, a compound which is not end-sealed and has an alcoholic hydroxyl group at the end is particularly preferable.

Examples of the aliphatic monoalcohol include linear, branched chain, and alicyclic monoalcohols having 1 to 9 carbon atoms. Examples of such aliphatic monoalcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 1-pentanol, isopentyl alcohol and tert-pentyl. Examples thereof include alcohol, cyclopentanol, 1-hexanol, cyclohexanol, 1-heptanol, 1-octanol, 2-ethyl-1-hexanol, isononyl alcohol and 1-nonyl alcohol.

These aliphatic monoalcohols may be used alone or in combination of two or more.

The aromatic monoalcohol refers to a compound having at least one aromatic ring structure in the molecule and one hydroxyl group. The hydroxyl group may be directly bonded to the aromatic ring, or may be bonded to another functional group such as an alkyl group bonded to the aromatic ring. A particularly preferable form of the aromatic monoalcohol is one in which a hydroxyl group is bonded to an alkyl group bonded to an aromatic ring. The aromatic monoalcohol preferably has 6 to 20 carbon atoms, more preferably 6 to 15 carbon atoms, and particularly preferably 6 to 10 carbon atoms.

Examples of the aromatic monoalcohol include phenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, 2-ethylphenol, 3-ethylphenol, 4-ethylphenol, 2,3-dimethylphenol, 2, 4-dimethylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2-propylphenol, 4-propylphenol, 2,3,5-trimethyl Aroma in which hydroxyl groups such as phenol, 2,3,6-trimethylphenol, 2,4,6-trimethylphenol, 1-naphthol, 2-naphthol, 2-phenylphenol and 4-phenylphenol are directly bonded to the aromatic ring. Group monoalcohol; benzyl alcohol, 2-methylbenzyl alcohol, 3-methylbenzyl alcohol, 4-methylbenzyl alcohol, 2-ethylbenzyl alcohol, 3-ethylbenzyl alcohol, 4-ethylbenzyl alcohol, 2,3-dimethylbenzyl alcohol , 2,4-dimethylbenzyl alcohol, 3,5-dimethylbenzyl alcohol, 2,6-dimethylbenzyl alcohol, 4-isopropylbenzyl alcohol, 2,4,6-trimethylbenzyl alcohol, 3,4,5-trimethylbenzyl alcohol , 1-phenylethanol, 2-phenylethanol, 3-phenyl-1-propanol and the like, and examples thereof include aromatic monoalcohol in which a hydroxyl group is bonded to another functional group bonded to the aromatic ring.

Among these aromatic monoalcohols, preferably phenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, 2-ethylphenol, 3-ethylphenol, 4-ethylphenol, 4-propylphenol, benzyl Alcohol, 2-methylbenzyl alcohol, 3-methylbenzyl alcohol, 4-methylbenzyl alcohol, 2-ethylbenzyl alcohol, 3-ethylbenzyl alcohol, 4-ethylbenzyl alcohol, 4-isopropylbenzyl alcohol, 1-phenylethanol, 2 −Phenylethanol, 3-phenyl-1-propanol, 2-phenylphenol and 4-phenylphenol, more preferably phenol, 2-methylphenol, 3-methylphenol, 4-methylphenol, benzyl alcohol, 2- Methylbenzyl alcohol, 3-methylbenzyl alcohol, 4-methylbenzyl alcohol, 1-phenylethanol and 2-phenylethanol, with particular preference being benzyl alcohol, 2-methylbenzyl alcohol, 3-methylbenzyl alcohol, 4-methylbenzyl. Alcohol, 1-phenylethanol and 2-phenylethanol.

These aromatic monoalcohols may be used alone or in combination of two or more.

n indicates the number of repeating units. n is an integer of 1 or more, usually 1 to 20, preferably 2 to 15, and more preferably 3 to 10. If it is in the upper range, it has excellent compatibility with the cellulose ester resin and also has an excellent effect of imparting plasticity.

The number average molecular weight of the ester compound is preferably 500 to 2500, more preferably 700 to 2000, and particularly preferably 800 to 1800. When the number average molecular weight of the ester compound is within the above range, the modifier for cellulose ester resin has excellent bleeding resistance even under high temperature and high humidity, and is difficult to volatilize even under high temperature conditions such as the film manufacturing process. Contamination of process equipment and working environment can be suppressed and improved. The number average molecular weight is a value measured by gel permeation chromatography (GPC) in terms of polystyrene using tetrahydrofuran (THF) as an eluent. Detailed measurement conditions will be described in Examples.

The ester compound preferably has an acid value of 3 mgKOH / g or less, more preferably 1 mgKOH / g or less, and particularly preferably 0.7 mgKOH / g or less.

Here, the acid value of "3 mgKOH / g or less" means that the acid value is "more than 0 mgKOH / g and 3 mgKOH / g or less". The lower limit thereof is preferably 0.05 mgKOH / g, more preferably 0.001 mgKOH / g, and particularly preferably 0.0001 mgKOH / g.

The acid value is derived from an ester compound having a carboxyl group at the terminal and not sealed with a monoalcohol at the end, which can be produced when a dihydric alcohol reacts with an aliphatic dicarboxylic acid. An ester having a carboxyl group at the terminal contained in the modifier for cellulose ester resin in order to impart excellent moisture permeability to the film and maintain the stability of the modifier for cellulose ester resin itself. The content of the compound is preferably as small as possible, and as a guideline, the acid value is preferably within the above range.

When the ester compound is terminally sealed, it preferably has a hydroxyl value of 30 mgKOH / g or less, more preferably 25 mgKOH / g or less, and particularly preferably 15 mgKOH / g or less.

Here, the hydroxyl value of "30 mgKOH / g or less" means that the hydroxyl value is "more than 0 mgKOH / g and 30 mgKOH / g or less". The lower limit thereof is preferably 0.1 mgKOH / g, more preferably 0.01 mgKOH / g, and particularly preferably 0.001 mgKOH / g.

When the ester compound is not terminal-sealed, it preferably has a hydroxyl value of 40 to 250 mgKOH / g, more preferably 50 to 200 mgKOH / g, and particularly preferably 60 to 150 mgKOH / g.

The hydroxyl value is derived from the hydroxyl group present at the terminal of the ester compound that can be produced when the dihydric alcohol reacts with the aliphatic dicarboxylic acid. Since the hydroxyl group has a strong affinity for water, the hydroxyl value should be small in order to maintain the moisture permeation resistance of the obtained film. On the other hand, the presence of the hydroxyl group has the effect of increasing the compatibility with the cellulose ester resin and enhancing the bleed resistance. Therefore, in order to balance the moisture permeation resistance and the bleed resistance of the obtained film, it is preferable that the hydroxyl value is within the above range.

<Manufacturing method of ester compound>
The ester compound can be obtained by reacting the aliphatic dicarboxylic acid with the divalent alcohol (aromatic divalent alcohol and aliphatic dihydric alcohol). Specifically, the aliphatic dicarboxylic acid, the aromatic dihydric alcohol, and the aliphatic dihydric alcohol, and if necessary, a terminal sealant, if necessary, in the presence of an esterification catalyst. For example, the ester compound can be produced by subjecting it to an esterification reaction in a temperature range of 100 to 250 ° C. for about 10 to 25 hours by a well-known and commonly used method. The conditions such as the temperature and time of the esterification reaction are not particularly limited and can be set as appropriate.

As the aliphatic dicarboxylic acid, the aromatic dihydric alcohol, the aliphatic dihydric alcohol, and the terminal encapsulant, the above-mentioned ones can be used. The ratio of each of the above components used in the production varies depending on the type of the component used, the characteristics of the target plasticizer, the molecular weight, and the like. Generally, it is used in a ratio of 10 to 80% by weight of an aliphatic dicarboxylic acid and 10 to 80% by weight of a dihydric alcohol. When an end-capping agent is used, it is used in a ratio of 10 to 80% by weight of the aliphatic dicarboxylic acid, 10 to 80% by weight of the dihydric alcohol, and 1 to 50% by weight of the end-capping agent.

Here, the dihydric alcohol has a molar ratio of the aliphatic dihydric alcohol to the aromatic dihydric alcohol in the ester compound in the range of 95: 5 to 20:80, and the total amount thereof is the above. Adjust appropriately so that it is within the range. The resulting ester compound, for example, in the formula (1), ^{A 1} is an aliphatic dicarboxylic acid residue, ^{G 1} is a divalent alcohol residue of an aromatic and ^{(A 1 -G 1), A} 1 Is an aliphatic dicarboxylic acid residue, and G ¹ is randomly bound to an aliphatic dihydric alcohol residue (A ^1- G ¹ ).

Examples of the esterification catalyst include at least one kind of metal and organometallic compound selected from the group consisting of Group 2, Group 3, and Group 4 of the periodic table. Specifically, metals such as titanium, tin, zinc, aluminum, zirconium, magnesium, hafnium, germanium; titanium tetraisopropoxide, titanium tetrabutoxide, titaniumoxyacetylacetonate, tin octanate, 2-ethylhexanetin, Examples thereof include metal compounds such as acetylacetonate zinc, zirconium tetrachloride, zirconium tetrachloride tetrahydrofuran complex, hafnium tetrachloride, hafnium tetrachloride tetrahydrofuran complex, germanium oxide, and tetraethoxygermanium. Titanium alcoxides such as titanium tetraisopropoxide, titanium tetrabutoxide, and titanium oxyacetylacetonate are preferable from the viewpoints of reactivity, ease of handling, and storage stability of the polyester compound obtained by the esterification reaction.

The esterification catalyst is preferably used in an amount of about 0.005 to 0.05 parts by weight based on 100 parts by weight of the total amount of the aliphatic dicarboxylic acid and the dihydric alcohol. When an end-capping agent is used, the esterification catalyst is 0.005 to 0. For 100 parts by weight of the total amount of the aliphatic dicarboxylic acid, the dihydric alcohol, and the end-capping agent. It is preferable to use about 05 parts by weight.

The modifier for cellulose ester resin of the present invention contains the ester compound, and is preferably composed of the ester compound. As the modifier for cellulose ester resin of the present invention, the product obtained by the above production method can be used as it is without purification. In this case, not only the ester compound but also other impurities are included, but the action of the modifier is not particularly inhibited.

The modifier for cellulose ester resin of the present invention is in a liquid state or a solid state, although it varies depending on the number average molecular weight and composition of the constituent ester compounds.

2. 2. Cellulose ester resin composition The cellulose ester resin composition of the present invention is a resin composition containing a cellulose ester resin and a modifier for the cellulose ester resin. The cellulose ester resin composition of the present invention preferably contains about 3 to 30 parts by weight of the modifier for cellulose ester resin with respect to 100 parts by weight of the cellulose ester resin, and more preferably about 4 to 25 parts by weight. , 5 to 20 parts by weight is particularly preferable. A film having excellent transparency and moisture permeability can be produced if the resin composition has a composition within the above range.

The cellulose ester resin is a cellulosic mixed fatty acid ester (cellulose acylate) mainly composed of cellulose acetate. The cellulose used as a raw material for cellulose acylate is not particularly limited, and examples thereof include cotton linter, wood pulp (derived from coniferous trees and derived from broad-leaved trees), and kenaf. Further, the cellulose esters obtained from them can be mixed and used in any ratio. The most common method of industrial synthesis of mixed fatty acid esters of cellulos is to use cellulos with fatty acids corresponding to acetyl groups and other acyl groups (acetic acid, propionic acid, valeric acid, etc.) or their acid anhydrides. It is a method of acylating with a mixed organic acid component containing. Examples of cellulose acylate include L-20, L-30, L-50, L-70, LT-55 (manufactured by Daicel Co., Ltd.) and CA-394-60LF (manufactured by Eastman Chemical Company). Commercial products such as, etc. can also be used.

The cellulose ester resin composition of the present invention may contain other components as long as the effects of the present invention are not impaired. Examples of other components include additives other than the above, such as polyester modifiers, plasticizers, moisture proofing agents, retardation expressing agents, ultraviolet absorbers, infrared absorbers, inorganic fine particles, and dyes. As these additives, known ones that are usually used can be used.

3. 3. Optical Film The optical film of the present invention is a film containing the cellulose ester resin composition.

The optical film of the present invention can be obtained by molding the cellulose ester resin composition into a film. Examples of the molding method include a method in which the cellulose ester resin composition is melt-kneaded with an extruder or the like and molded into a film by using a T-die or the like. It can also be obtained by molding by a solution casting method in which the resin solution obtained by uniformly dissolving and mixing the cellulose ester resin composition in an organic solvent is cast on a support and dried. In the case of the solution casting method, the orientation of the cellulose ester resin in the film during molding can be suppressed, so that the obtained film exhibits substantially optical isotropic properties. This film exhibiting optical isotropic properties can be used as an optical film as a member of a liquid crystal display or the like, and is useful as a polarizing plate protective film or an optical compensation film (for an IPS drive type liquid crystal display).

Hereinafter, the present invention will be described in more detail with reference to Synthesis Examples, Examples and Comparative Examples, but the scope of the present invention is not limited by these Examples.

<Measurement method>
(A) Acid value of ester compound 60 g of a solvent of THF / ethanol = 5/1 (weight ratio) is placed in an Erlenmeyer flask. Phenolphthalein is added thereto as an indicator, and titrated with a 0.1 mol / l sodium hydroxide aqueous solution until a slight red color is confirmed. An arbitrary amount of sample is weighed therein, completely dissolved, and then titrated with a 0.1 mol / l sodium hydroxide aqueous solution until a slight red color is confirmed. From the titration result, the acid value is calculated by the following formula.

(B) Hydroxyl value of ester compound 5 g of a sample is weighed in an iodine flask, 5 ml of a mixed solution of pyridine / acetic anhydride = 7/1 (weight ratio) is added, and an air-cooled tube is attached. This iodine flask is heated on a water bath for 1.5 hours, then 5 ml of water is added from the upper part of the air cooling tube, and the mixture is heated again for 10 minutes. After cooling to room temperature, the inner wall of the air-cooled pipe is washed away with 50 ml of ethanol, and then the air-cooled pipe is removed. Phenolphthalein is added as an indicator and titrated with 0.5 mol / l aqueous sodium hydroxide solution until a slight crimson color is confirmed.

Separately, a blank test is performed by the same operation, and the hydroxyl value is calculated from these titration results by the following formula.

(C) Number average molecular weight of ester compound Measured by GPC Equipment used: HLC-8320 (manufactured by Tosoh Corporation)
Column: TSKgel SuperHZ3000 + TSKgel Super
HZ2000 + TSKgel SuperHZ1000 1 each in series Solvent: THF
Flow rate: 0.3 ml / min
Detector: RI

(D) The moisture permeability test piece and operation of the film conform to JIS Z0218.

However, as an accelerated test, the temperature condition was set to 50 ° C., and the value calculated by the calculation method described in JIS Z0218 using the weight difference between the cups 1 hour and 3 hours after the start of the test was used as the measured value, and the film thickness was calculated by the following formula. Was converted to 80 μm and used as the moisture permeability.

(E) Film transparency (haze)
Compliant with JIS K7136.
Equipment used: HazeMeterNDH 4000 (manufactured by Nippon Denshoku Industries Co., Ltd.)

<Raw materials used>
Cellulose ester resin: Cellulose acetate (LT-55 manufactured by Daicel Corporation)
Phosphoric acid ester plasticizer 1: Triphenyl phosphate (TPP)
Phosphate ester plasticizer 2: Biphenyldiphenyl phosphate (BDP)
Ester compounds A to G: Ester compounds synthesized in Examples and Comparative Examples described later.

<Synthesis of ester compounds>
Example 1
Synthesis of Ester Compound A 129 g (0.9 mol) of 1,4-benzenedimethanol and 1,2-benzenedimethanol as dihydric alcohol in a 500 ml glass four-necked round-bottom flask equipped with a stirrer, a thermometer and a rectifying device. After charging 177 g (2.3 mol) of propanediol, 182 g (1.5 mol) of succinic acid as an aliphatic dicarboxylic acid, and 0.06 g of tetrabutyl titanate as a catalyst, the temperature was raised to 200 ° C. at normal pressure for 5.5 hours. It was warm. During the temperature rise, the outflowing gas was condensed through a rectifying device, separated into water produced by the reaction and others, the water was recovered, and the others were returned to the flask. After that, the rectification device was removed, a distilling head, a cooling tube, and a 200 ml eggplant flask were attached to the round bottom flask, and the temperature was raised again to 220 ° C. at normal pressure over 5.5 hours, and 220 ° C. for 2.5 hours. Retained. During this time, the water produced by the reaction was collected in a 200 ml eggplant flask. Then, a decompression device was attached, the pressure was reduced to 2.3 kPa, the temperature was raised to 170 ° C. over 6 hours, and polycondensation was performed. As a result, 328 g of a yellow transparent high-viscosity liquid containing the following formula as a main component was obtained. The number average molecular weight of the ester compound A was 1550, the acid value was 0.24 mgKOH / g, and the hydroxyl value was 108 mgKOH / g.

Example 2
Synthesis of Ester Compound B 116 g (1.1 mol) of benzyl alcohol as an aromatic monoalcohol and 1,4- as a dihydric alcohol in a 500 ml glass four-necked round bottom flask equipped with a stirrer, a thermometer and a rectifying device. After charging 79 g (0.6 mol) of benzenedimethanol and 87 g (1.1 mol) of 1,2-propanediol, 170 g (1.4 mol) of succinic acid as an aliphatic dicarboxylic acid, and 0.06 g of tetrabutyl titanate as a catalyst. The temperature was raised to 230 ° C. at normal pressure over 9 hours. During the temperature rise, the outflowing gas was condensed through a rectifying device, separated into water produced by the reaction and others, the water was recovered, and the others were returned to the flask. After cooling until the outflow of gas stopped, the rectification device was removed, the distilling head, the condenser, and the 200 ml eggplant flask were attached to the round-bottom flask, and the temperature was raised again to 230 ° C. at normal pressure over 2 hours to 230. The temperature was kept at 30 minutes. Then, a decompression device was attached, and the temperature was maintained at 160 to 180 ° C. for 2 hours under a decompression of 13.3 kPa. The water produced by the reaction was collected in a 200 ml eggplant flask between the temperature rise at normal pressure and the temperature maintenance at reduced pressure. Then, the pressure was reduced to 0.4 kPa, and then the temperature was raised to 180 ° C. over 6.5 hours to carry out polycondensation. As a result, 299 g of a yellowish brown transparent high-viscosity liquid containing the following formula as a main component was obtained. The number average molecular weight of the ester compound B was 1220, the acid value was 0.20 mgKOH / g, and the hydroxyl value was 11.8 mgKOH / g.

Comparative Example 1
Synthesis of Ester Compound C 190 g (1.8 mol) of benzyl alcohol as an aromatic monoalcohol and 1,4 as a dihydric alcohol in a 1 L glass four-necked round-bottom flask equipped with a stirrer, a thermometer, and a rectifying device. After charging 211 g (1.5 mol) of -benzenedimethanol, 232 g (2.0 mol) of succinic acid as an aliphatic dicarboxylic acid, and 0.07 g of tetrabutyl titanate as a catalyst, the temperature was raised to 210 ° C. over 11 hours at normal pressure. It was warm. During the temperature rise, the outflowing gas was condensed through a rectifying device, separated into water produced by the reaction and others, the water was recovered, and the others were returned to the flask. Then, the rectifying device was removed, a distilling head and a cooling tube, a 200 ml eggplant flask, and a decompression device were attached to the round bottom flask, and the temperature was maintained at 160 to 190 ° C. for 12 hours under a decompression of 13.3 kPa. During the reduced pressure, the water produced by the reaction was collected in a 200 ml eggplant flask. Then, the pressure was reduced to 0.4 kPa, and then the temperature was raised to 180 ° C. over 4.5 hours to carry out polycondensation. As a result, 423 g of a yellowish brown solid containing the following formula as a main component was obtained. The number average molecular weight of the ester compound C was 1000, and the acid value was 0.29 mgKOH / g.

Comparative Example 2
Synthesis of Ester Compound D As a dihydric alcohol, 590 g (6.6 mol) of 1,3-butanediol as a divalent carboxylic acid in a 1 L glass four-necked round-bottom flask equipped with a stirrer, a thermometer, and a rectifying device. After charging 292 g (2.0 mol) of adipic acid, 166 g (1.0 mol) of terephthalic acid, and 0.11 g of tetrabutyl titanate as a catalyst, the temperature was raised to 230 ° C. over 10 hours at normal pressure. During the temperature rise, the outflowing gas was condensed through a rectifying device, separated into water produced by the reaction and others, the water was recovered, and the others were returned to the flask. After cooling until the outflow of gas stopped, the rectification device was removed, the distilling head, the condenser, and the 200 ml eggplant flask were attached to the round-bottom flask, and the temperature was raised again to 230 ° C. at normal pressure over 2 hours to 230. The temperature was kept at 16 hours. During this time, the water produced by the reaction was collected in a 200 ml eggplant flask. Then, a decompression device was attached, the pressure was reduced to 0.4 kPa, and then the temperature was raised to 160 ° C. over 5.5 hours for polycondensation. After cooling, the pressure was returned to normal pressure, 177 g (1.7 mol) of acetic anhydride was added, and the temperature was maintained at 120 ° C. for 4 hours. Then, the pressure was reduced to 2 kPa while maintaining 120 ° C., and the low boiling point was recovered. As a result, 727 g of a yellowish brown transparent liquid containing the following formula as a main component was obtained. The number average molecular weight of the ester compound D was 1300, the acid value was 0.44 mgKOH / g, and the hydroxyl value was 0.24 mgKOH / g.

Comparative Example 3
Synthesis of Ester Compound E As a dihydric alcohol, 367 g (4.8 mol) of 1,2-propanediol as a divalent carboxylic acid in a 1 L glass four-necked round-bottom flask equipped with a stirrer, a thermometer, and a rectifying device. After charging 461 g (3.2 mol) of adipic acid and 0.13 g of tetrabutyl titanate as a catalyst, the temperature was raised to 180 ° C. at normal pressure over 7.5 hours. During the temperature rise, the outflowing gas was condensed through a rectifying device, separated into water produced by the reaction and others, the water was recovered, and the others were returned to the flask. After that, the rectification device was removed, a distilling head and a cooling tube, a 200 ml eggplant flask, and a decompression device were attached to the round bottom flask, and the pressure was reduced to 0.7 kPa over 15.5 hours, and then the temperature was raised to 180 ° C. Was done. After cooling, the pressure was returned to normal pressure, 204 g (2.0 mol) of acetic anhydride was added, and the temperature was maintained at 120 ° C. for 4 hours. Then, the pressure was reduced to 1.3 kPa while maintaining 120 ° C., and the low boiling point was recovered. As a result, 697 g of a pale yellow transparent liquid containing the following formula as a main component was obtained. The number average molecular weight of the ester compound E was 1400, the acid value was 0.20 mgKOH / g, and the hydroxyl value was 0.10 mgKOH / g.

Comparative Example 4
Synthesis of Ester Compound F As dihydric alcohol 365 g (4.8 mol) as divalent carboxylic acid in a 1 L glass four-necked round-bottom flask equipped with a stirrer, thermometer and rectifying device. After charging 467 g (3.2 mol) of adipic acid and 0.13 g of tetrabutyl titanate as a catalyst, the temperature was raised to 180 ° C. at normal pressure over 4 hours. During the temperature rise, the outflowing gas was condensed through a rectifying device, separated into water produced by the reaction and others, the water was recovered, and the others were returned to the flask. After cooling until the outflow of gas stopped, the rectifying device was removed, a distilling head, a condenser, and a 200 ml eggplant flask were attached to the round bottom flask, and the temperature was maintained at 180 ° C. for 4 hours. Then, a decompression device was attached to a round bottom flask, and the temperature was maintained at 170 to 180 ° C. for 11 hours under a decompression of 10.6 kPa. During this time, the water produced by the reaction was collected in a 200 ml eggplant flask. Then, the pressure was reduced to 0.7 kPa over 11.5 hours, the temperature was raised to 180 ° C., and polycondensation was performed. As a result, 591 g of a colorless transparent liquid containing the following formula as a main component was obtained. The number average molecular weight of the ester compound F was 1500, the acid value was 0.36 mgKOH / g, and the hydroxyl value was 108 mgKOH / g.

Comparative Example 5
Synthesis of Ester Compound G 433 g of 1,4-benzenedimethanol as a divalent alcohol in a 1 L glass four-necked round-bottom flask equipped with a stirrer, thermometer, distilling head, condenser, and 200 ml eggplant flask. 1 mol), 252 g (2.1 mol) of succinic acid as an aliphatic dicarboxylic acid, and 0.07 g of tetrabutyl titanate as a catalyst were charged, and then the temperature was raised to 250 ° C. at normal pressure over 26.5 hours. During the temperature rise, the outflowing gas was condensed through a cooling pipe and collected in a 200 ml eggplant flask. Then, a decompression device was attached to a round bottom flask, and the temperature was maintained at 190 to 210 ° C. for 12 hours under a decompression of 2.0 kPa. During the reduced pressure, the water produced by the reaction was collected in a 200 ml eggplant flask. As a result, 601 g of a yellow solid having the following formula as a main component was obtained. The acid value of the ester compound G was 0.39 mgKOH / g.

<Film creation and evaluation>
Example 11
A solution prepared by dissolving 2.14 g of cellulose ester resin and 0.26 g of ester compound A in a mixed solvent of 34.0 g of methylene chloride, 4.8 g of methanol and 1.2 g of butanol was weighed in a petri dish having a diameter of 94 mm, and covered. Later, it was made to flow throughout the petri dish. Then, the film was allowed to stand overnight at room temperature while being kept horizontal, and then dried at 50 ° C. for 0.5 hours and then at 100 ° C. for 1 hour to obtain a film having a thickness of 27 μm. Table 1 shows the results of measuring the moisture permeability and transparency of the obtained film by the above method.

Example 12
The same operation as in Example 1 was carried out except that the ester compound B was used instead of the ester compound A to obtain a film having a thickness of 27 μm. Table 1 shows the results of measuring the moisture permeability and transparency of the obtained film by the above method.

Comparative Example 11
The same operation as in Example 1 was carried out except that the ester compound C was used instead of the ester compound A to obtain a film having a thickness of 28 μm. Table 1 shows the results of measuring the moisture permeability and transparency of the obtained film by the above method.

Comparative Example 12
The same operation as in Example 1 was carried out except that the ester compound D was used instead of the ester compound A to obtain a film having a thickness of 26 μm. Table 1 shows the results of measuring the moisture permeability and transparency of the obtained film by the above method.

Comparative Example 13
The same operation as in Example 1 was carried out except that the ester compound E was used instead of the ester compound A to obtain a film having a thickness of 26 μm. Table 1 shows the results of measuring the moisture permeability and transparency of the obtained film by the above method.

Comparative Example 14
The same operation as in Example 1 was carried out except that the ester compound F was used instead of the ester compound A to obtain a film having a thickness of 25 μm. Table 1 shows the results of measuring the moisture permeability and transparency of the obtained film by the above method.

Comparative Example 15
The same operation as in Example 1 was carried out except that the ester compound G was used instead of the ester compound A to obtain a film having a thickness of 29 μm. Table 1 shows the results of measuring the moisture permeability and transparency of the obtained film by the above method.

Comparative Example 16
The same operation as in Example 1 was carried out except that the phosphoric acid ester-based plasticizer 1 was used instead of the ester compound A, to obtain a film having a thickness of 25 μm. Table 1 shows the results of measuring the moisture permeability and transparency of the obtained film by the above method.

Comparative Example 17
The same operation as in Example 1 was carried out except that the phosphoric acid ester-based plasticizer 2 was used instead of the ester compound A, to obtain a film having a thickness of 24 μm. Table 1 shows the results of measuring the moisture permeability and transparency of the obtained film by the above method.

Comparative Example 18
The same operation as in Example 1 was carried out except that the ester compound A was not used, to obtain a film having a thickness of 24 μm. Table 1 shows the results of measuring the moisture permeability and transparency of the obtained film by the above method.

Films containing an ester compound in which an aromatic dihydric alcohol and an aliphatic dihydric alcohol are used in combination as dihydric alcohols as in Examples 11 and 12 are aromatic as dihydric alcohols as in Comparative Examples 11 to 15. Compared with a film containing an ester compound using only one of a dihydric alcohol and an aliphatic dihydric alcohol, or a film containing a conventionally used phosphoric acid ester-based plasticizer such as Comparative Examples 16 and 17. It can be seen that the moisture permeability is clearly low, the moisture permeability is improved, and the transparency (haze value) is also excellent. Further, a film containing an ester compound in which an aromatic dihydric alcohol and an aliphatic dihydric alcohol are used in combination as a dihydric alcohol as in Examples 11 and 12 is an aromatic dicarboxylic acid as a dibasic acid as in Comparative Example 12. It can be seen that the film has excellent moisture permeation resistance as compared with a film containing an ester compound in which an acid and an aliphatic dicarboxylic acid are used in combination. From these facts, it can be seen that by including the ester compound having the composition of the present invention as a modifier, the moisture permeation resistance can be improved while maintaining the transparency of the film.

Claims (8)

The following formula (1) or (2):

[In formulas (1) and (2), A ¹ , A ² and A ³ represent the same or different aliphatic dicarboxylic acid residues. G ¹ , G ² and G ³ indicate the same or different divalent alcohol residues, and the divalent alcohol residues include aliphatic dihydric alcohol residues and aromatic dihydric alcohol residues. .. n is an integer of 1 or more. ]
A modifier for a cellulose ester resin containing an ester compound having a structure represented by .
Ester compounds having the structure represented by the formula (1) are aromatic in dihydric alcohol residue represented by G ¹ in or both ends are sealed with an aromatic monoalcohol, or the formula (1) From the group consisting of hydroquinone, resorcinol, 1,2-benzenedimethanol, 1,4-benzenedimethanol, 1,2-benzenediethanol and 1,4-benzenediethanol, the same or different dihydric alcohol residues. At least one alcohol residue to be selected and
Ester compounds having the structure represented by the formula (2) is represented by G ² and G ³ in or both ends has an alcoholic hydroxyl group without being sealed, or the formula (2) The aromatic dihydric alcohol residues in the dihydric alcohol residues are the same or different, hydroquinone, resorcinol, 1,2-benzenedimethanol, 1,4-benzenedimethanol, 1,2-benzenediethanol and 1, A modifier for a cellulose ester resin, which is at least one alcohol residue selected from the group consisting of 4-benzenediethanol . The modifier for a cellulose ester resin according to claim 1, wherein the ester compound has a number average molecular weight of 500 to 2500. The cellulose ester according to claim 1 or 2, wherein the molar ratio of the aliphatic dihydric alcohol residue to the aromatic dihydric alcohol residue in the ester compound is 95: 5 to 20:80. Modifier for resin. The cellulose ester according to any one of claims 1 to 3, wherein the ester compound has a structure represented by the formula (2) and has an alcoholic hydroxyl group without sealing both ends. Modifier for resin. The modifier for a cellulose ester resin according to any one of claims 1 to 3, wherein the ester compound has a structure represented by the formula (1) and both ends are sealed with an aromatic monoalcohol. .. The modifier for a cellulose ester resin according to any one of claims 1 to 5 , wherein the acid value of the ester compound is 3 mgKOH / g or less. A cellulose ester resin composition containing the modifier for a cellulose ester resin according to any one of claims 1 to 6 and a cellulose ester resin. An optical film containing the cellulose ester resin composition according to claim 7 .